Screening of pair fluctuations in superconductors with coupled shallow and deep bands: A route to higher-temperature superconductivity

Year: 2019

Authors: Salasnich L., Shanenko AA., Vagov A., Aguiar JA., Perali A.

Autors Affiliation: Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Via Marzolo 8, I-35131 Padua, Italy; CNR, INO, Sez Sesto Fiorentino, Via Nello Carrara 2, I-50019 Sesto Fiorentino, Italy; Univ Fed Pernambuco, Dept Fis, Av Jorn Anibal Fernandes S-N,Cidade Univ, BR-50740560 Recife, PE, Brazil; Bayreuth Univ, Inst Theoret Phys 3, D-95440 Bayreuth, Germany; ITMO Univ, 49 Kronverksky Pr, St Petersburg 197101, Russia; Univ Camerino, Phys Unit, Sch Pharm, I-62032 Camerino, Italy

Abstract: A combination of strong Cooper pairing and weak superconducting fluctuations is crucial to achieve and stabilize high-T-c, superconductivity. We demonstrate that a coexistence of a shallow carrier band with strong pairing and a deep band with weak pairing, together with the Josephson-like pair transfer between the bands to couple the two condensates, realizes an optimal multicomponent superconductivity regime: it preserves strong pairing to generate large gaps and a very high critical temperature but screens the detrimental superconducting fluctuations, thereby suppressing the pseudogap state. Surprisingly, we find that the screening is very efficient even when the interband coupling is very small. Thus, a multiband superconductor with a coherent mixture of condensates in the BCS regime (deep band) and in the BCS-BEC crossover regime (shallow band) offers a promising route to higher critical temperatures.


Volume: 100 (6)      Pages from: 064510-1  to: 064510-9

DOI: 10.1103/PhysRevB.100.064510

Citations: 17
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